1. Field of the Invention
The present invention relates to an ejection status determining method determining an ink ejection status of an inkjet printing head having a heating element (heater) generating thermal energy as energy utilized for ejecting the ink from a nozzle.
2. Description of the Related Art
Among the inkjet printing methods which eject ink for example, in a droplet form, from an ejection opening, and apply it to paper, plastic film, and other printing media, there exists one using a printing head having a heater generating thermal energy as energy utilized for ejecting the ink. This method has such advantages as that a high-resolution printing can be realized, and that a high density mounting of nozzles is facilitated, because an electro-thermal transducer element generating heat in response to a supplied current, its drive circuit and the like can be formed using a process like a semiconductor manufacturing process, for example.
On the other hand, also in the printing head according to this method, an ejection-failure may occur in all of or a part of the nozzles of the printing head, due to such causes as clogging of the nozzle caused by a foreign matter, thickened ink or the like, a bubble mixed in an ink supply path or the nozzle, or variations of wettability of the nozzle forming face of the printing head. In order to avoid deterioration of image quality caused in the case of such ejection-failure occurrence, it is preferred to carry out promptly a recovery operation recovering the ejection status and a complement operation by using other nozzles. However, in order to carry out these operations promptly, it has been an extremely important subject to carry out accurately and timely determination of the ejection status or determination of the ejection-failure occurrence.
Then, conventionally, various ejection status determination methods and complementing methods, or apparatuses to which these are applied have been proposed.
In Japanese Patent Laid-Open No. H6-79956 (1994), as a print method acquiring an image without image defects by detecting a printed matter, disclosed is a configuration which prints a predetermined pattern on the paper for the detection, and reads it by a reader to detect an abnormal print element. According to Japanese Patent Laid-Open No. H6-79956 (1994), an image without image defects can be acquired by moving image data to be applied to the abnormal print element, superimposing it on image data of other print element and complementing the printing thereof.
In Japanese Patent Laid-Open No. H3-234636 (1991), disclosed is a configuration provided with detecting means (reading head) for detecting whether an ink has been ejected or not in order to equalize ejection operations of nozzles disposed in a printing-medium width direction in a configuration using heads (line head) corresponding to the printing-medium width. Then, in Japanese Patent Laid-Open No. H3-234636 (1991), disclosed is also a configuration setting up a suitable control based on a driving condition of the nozzle at the time of the detection.
Furthermore, in Japanese Patent Laid-Open No. H2-194967 (1990), as a method detecting ink droplet flying, disclosed is a configuration determining an ejection status of the ink droplet at each ejection opening by detecting means having a pair of a light emitting device and a light receiving element disposed at one end and the other end of an ejection opening array of the printing head, respectively.
In Japanese Patent Laid-Open No. S58-118267 (1983), disclosed is a configuration which, without detecting an ejection status directly, utilizes a conductor part disposed in a position influenced by heat generated with a heater, and detects a change of a resistance of the conductor part varying depending on the temperature, that is, a method of carrying out detection in an ink source side is disclosed.
Furthermore in Japanese Patent Laid-Open No. H2-289354 (1990), disclosed is a configuration provided with heaters and a temperature detecting element on the same support member (heater board), such as a Si substrate, as the configuration in which detection is carried out in an ink ejection source side. In this Japanese Patent Laid-Open No. H2-289354 (1990), it is described that the temperature detecting element formed in a film shape is provided so that it overlaps with the arraying area of the heaters. In this Japanese Patent Laid-Open No. H2-289354 (1990), it is described that non-ejection is determined from a change in a resistance of the temperature detecting element in response to the temperature change. Furthermore, it is also described that a film-shaped temperature detecting element is formed on the heater board by means of a film-forming process, and is connected, via a terminal, with the outside by using such a method as a wire bonding.
However, in the ejection status determination method disclosed in Japanese Patent Laid-Open No. H6-79956 (1994), a nozzle in an ejection-failure status is detected from the result acquired by reading a check pattern printed on a sheet of paper. Accordingly, printing of the check pattern before the determination is a prerequisite, and it is extremely difficult to carry out the ejection status determination promptly. It is necessary to provide a reader, thereby increasing size and cost of the printing apparatus.
Also in the configurations disclosed in Japanese Patent Laid-Open Nos. H3-234636 (1991) and H2-194967 (1990), it is difficult to reduce size and cost of the apparatus, and is also difficult to detect promptly the nozzle having an ejection-failure.
Furthermore, in the configurations disclosed in Japanese Patent Laid-Open Nos. S58-118267 (1983) and H2-289354 (1990), the problems associated with Japanese Patent Laid-Open Nos. H6-79956 (1994), H3-234636 (1991) and H2-194967 (1990) are considered to be mitigated. However, in view of determining the ejection status accurately, it is still insufficient, and especially, in Japanese Patent Laid-Open No. H2-289354 (1990), a nozzle in an ejection-failure status cannot be specified exactly, either.